Check this out...I'm going about rebuilding my first Benz..a 1982 300SD I'm working on the 3/2 vacuum "situation" and I see this strange sensor where there should be a vacuum thermo valve


So I bought a thermo vac valve, and the diameter of the threads is significantly smaller than the hole this sensor is mounted into...can anyone shed some light here? I cant find any info about this in the FSM, or elsewhere...maybe I havent looked hard enough?

another view..


any info you vets could share with this n00b would be greatly appreciated!!